This invention relates to a cam for use with rotating grinding machines that may be adjusted to achieve a desired dimension.
A dog bone shaped part 20 that is typically formed by grinding equipment is illustrated in Prior Art FIG. 1 and consists of portions 22 having an inner end 24 and a curved outer end 26. A central portion 28 connects the portions 22.
The distance between the outer ends 26 of portions 22 is defined as a dimension Y and the width of portions 22 is defined as a dimension X, a dimension R is defined as the radius of the portions 22. Each of these three dimensions must be accurately machined to within close tolerances.
A cam 30 known in the prior art is shown in Prior Art FIG. 2 and consists of portions 32 that correspond to portions 22 of the part 20. Shaft 34 mounts cam 30 within a grinding apparatus and portions 32 of cam 30 form the desired dimensions and shape of portions 22 of dog bone part 20.
A typical prior art grinding apparatus is shown in Prior Art FIG. 3 and consists of cam 30 mounted within guide member 36 upon which a part 38 is connected at 40. Part 38, connection 40 and cam 30 are all driven to rotate within guide 36. A grinding wheel 42 is positioned such that part 38 is periodically brought into contact with it as cam 30 rotates along cam surface 44.
As shown in Prior Art FIG. 4, cam 30 rotates along cam surface 44 and guide member 36 is pivoted towards and away from grinding wheel 42 on pin 46 which is fixed in base 48. As cam 30 rotates on cam surface 44, guide 36 moves part 38, into and away from, grinding wheel 42 to form a surface corresponding to cam 30 on part 38. By ensuring the dimensions X, Y and R on cam 30 are accurate, part 38, formed by grinding wheel 42, will be accurately dimensioned.
In constructing prior art cam 30, problems were encountered since it is time consuming and expensive to accurately machine all three dimensions on a cam. This is particularly true when only a small run of dog bone parts 20 is to be run. In many instances, it was not economically feasible to create a cam 30 for a small run of parts 20. Several repeated grinding operations were required to change a piece of metal into a cam having the desired X, Y and R dimensions for a particular part.
It is therefore an object of the present invention to describe an adjustable cam that can be adjusted to correspond to a variety of dimensions and thus may be quickly and inexpensively tailored to suit the desired dimension of a particular dog bone part 20.